/*
 * 计算半圆弧长及半圆的面积。（3分）
 */

#include <stdio.h>

#define r 5.3
#define pi 3.14159

int main() {
	setbuf(stdout, NULL);

	float Area, circumference;

	Area = pi * r * r / 2;
	circumference = pi * r;

	printf("Area=%.5f\ncircumference=%.5f\n", Area, circumference);

	return 0;
}